SOLUTION: it takes 3 hours for a boat to ravel 27 mile upstram. the same boat can travel 30 miles down stream in 2 hours fond the speed of the boat and the current

Question 508467: it takes 3 hours for a boat to ravel 27 mile upstram. the same boat can travel 30 miles down stream in 2 hours fond the speed of the boat and the current
Answer by Maths68(1474) (Show Source): You can put this solution on YOUR website!
Let
Speed of boat = b
Speed of current = c
Given
Upstream
=====================================================
Distance = 27 miles
Time = 3 hours
Speed = Distance/time
Speed = 27/3
Speed = 9 miles per hour
We can say boat speed minus the speed of current
b-c=9..........(1)

Downstream
=====================================================
Distance = 30 hours
Time = 2 hours
Speed = Distance/time
Speed = 30/2
Speed = 15 miles per hour
We can say boat speed plus the speed of current
b+c=15.............(2)
Add (1) and (2)
b-c=9..........(1)
b+c=15.............(2)
---------
2b=24
b=24/2
b=12
Put the value of b in (2)
b+c=15.............(2)
12+c=15
c=15-12
c=3
===================================================
Speed of boat = b = 12 miles / hour
Speed of current = c = 3 miles / hour

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